1. Field of the Invention
The present invention generally relates to droplet discharging technology for discharging minute amounts of droplets, and in particular to a droplet discharging device capable of microencapsulating and discharging the object to be discharged (droplet), and to a manufacturing method of microcapsules.
2. Description of the Related Art
A microcapsule is generally composed of a content referred to as the core material, and a shell material which is a minute container for encapsulating this core material. Since a microcapsule possesses a function of protecting the core material from external environment and a function of adjusting the timing of being discharged to the outside, it is being used in a variety of fields such as pharmaceutical products, impact paper, aromatic substances, electrophoresis and so on.
This microcapsule is generally manufactured via the step of dispersing the core material into particulates in a suitable medium, and the step of coating such particles with the shell material. The ultrasonic wave method, homogenizer method, spray drying method or the like is employed for the levigation and micro-encapsulation of the core material.
For example, Japanese Patent Laid-Open Publication No. H05-285375 discloses an example of an ultrasonic wave method. In this example, employed is a probe device for generating ultrasonic waves from the tip of a metal probe composed of titanium or the like. The probe is dipped in a liquid containing keratin S-sulfur salt solution, organic solvent, core material and so on, and then subject to vibrational energy, whereby obtained is a microcapsule.
Further, for instance, Japanese Patent Laid-Open Publication No. H07-96167 discloses an example of the homogenizer method. In this example, while supplying an aqueous substance and hydrophobic substance, these are emulsified and dispersed with the high-speed rotation of a rotor, and the hydrophobic substance is thereby microencapsulated.
Nevertheless, the manufacture and use of microcapsules are estranged either in terms of time or space. A typical example of this would be when the place of manufacture and the place of use of such microcapsules differ, and this estrangement in terms of time or space leads to the deterioration in quality of the microcapsules. Appropriate storage and transport of the microcapsules will also become necessary.
Moreover, since a conventional manufacturing device of microcapsules adjusts the particle size of microcapsules via stirring, it is necessary to fill the microcapsule materials in the stirring container in an amount in which the stirring bar of the stirring mechanism will become buried to a certain degree. Thus, this is not suitable for production of microcapsules in slight or minute amounts. For example, since DNA fragment samples for forming a so-called DNA sensor (or DNA chip), medical drugs for testing and so on are extremely costly, problems will arise when these are to be microencapsulated.
In addition, a conventional manufacturing device of microcapsules is for producing one type in large amounts, and, when various microcapsules in which the particle size and core material selected arbitrarily are to be produced in minute amounts, the production efficiency is low.
Further, with a conventional manufacturing device of microcapsules, it is difficult to stir the material evenly, and distribution of the particle size of the manufactured microcapsules is broad. As a result, the nozzle hole of the droplet discharging device may clog up when applying the microcapsules with the droplet discharging method.